The present invention relates to display devices such as a Liquid Crystal Display (LCD) device and an organic ElectroLuminescent (EL) display device, and in particular, to a display device including a display section or area having a non-rectangular outer contour.
Description will now be given of a conventional display device.
Heretofore, there have been primarily employed Cathode Ray Tubes (CRT) devices as display devices. Recently, liquid crystal display devices of active matrix type which are planar display devices have been increasingly used due to space and power saving effects thereof. The LCD device is a display device using light transmission of a liquid crystal. The device does not emit light by itself, but controls light, i.e., backlight from a backlighting device through its states including a transmission state, an interruption state, and an intermediate state therebetween to thereby conducting gray scale or gradation display. Additionally, organic EL display devices which are also planar display devices have been put to practical uses. Heretofore, LCD devices have found application thereof primarily in products such as screens of notebook-sized personal computers and monitors of desktop personal computers. However, the LCD devices have been recently employed as display screens of Television sets and cellular phones. In the display devices employed in these apparatuses, it is desirable that the surface on the display side of the apparatus has a large display area ratio. The image display section serves functions as the intrinsic display device. Although the section enclosing the image display area, i.e., a frame section is an area required for the display operation, but is not particularly necessary for the user and is not desirable for the good design of the display. Reducing the frame section not directly contributing to the display for the user results in the realization of an efficient display function.
For the LCD devices having been used in many apparatuses, an attempt has been made to reduce or to narrow the frame area in each apparatus. Particularly, this effort is remarkably made for the notebook-sized personal computers. Although the notebook-sized personal computers in an early stage include quite a large frame area, the area is quite small at present.
The frame section includes wiring, circuits, and semiconductor devices required for the display operation of the LCD device. For example, JP-A-11-337966 describes a technique in which by constructing an efficient wiring pattern between semiconductors, the frame area is narrowed and the production cost is lowered. Additionally, JP-A-11-190857 describes a technique in which part of the circuit to drive the LCD device is integrally constructed in the panel and Indium Tin Oxide (ITO) wiring is employed to further reduce the circuit area to narrow the frame section and to improve yielding.
Description has been given of examples of display devices using liquid crystal. Similar efforts have been exerted also for display devices using organic EL elements.
However, the ideas to narrow the frame area is applied primarily to display devices including an image display area having a rectangular outer contour. In a display device having a rectangular outer contour, it is possible to construct an outer contour of the display section according to the directions of pixels orthogonally arranged in a shape of an orthogonal matrix.
On the other hand, recently, display devices having a non-rectangular outer contour have also been discussed. For example, the dashboard of a car has desirably a non-rectangular shape, and there may desirably exist an elliptic cellular and a heart-shaped cellular. In such cases in which the device has a non-rectangular outer contour, the outer contour of the display section is configured such that outer edges thereof are in directions different from those associated with the angles of the directions to arrange the pixels in the orthogonal matrix. This likely results in collision between wiring leader lines from the pixel display section and an internal driver circuit section. It is hence required that the circuit section is arranged on an outside location, and the frame area increases as a result.
In addition, the leader line is arranged to widely detour the internal driver circuit section and passes the outer side of the circuit section. This further increases the frame area and the wiring distance, leading to occurrence of a wiring delay. Additionally, by arranging the wiring to connect internal driver circuit sections on an outer side of the circuit section, it possibly occurs that the frame area further increases. Resultantly, the margin is too small to arrange the wiring, and hence the designing of the device is difficult depending on cases.
When the image display device having the non-rectangular display section as above includes a signal wiring internal circuit and a scanning wiring internal circuit, there appear an area of each internal circuit and a wiring area thereof as well as an overlapped area between the signal wiring internal circuit and the scanning wiring internal circuit. This leads to a problem of increase in the frame area. According to JP-A-11-337966 and JP-A-11-190857, the arrangement of the internal circuits in the display devices having a non-rectangular outer contour has not been discussed.